Re: Determining the number of clusters

Posted by LUCINDA M TEAR on Jun 16, 2006; 8:03pm
URL: http://spssx-discussion.165.s1.nabble.com/Determining-the-number-of-clusters-tp1069116p1069118.html

The following paper is an application of that kind of approach to clustering
sites using the frequency of occurrence and abundance of species at sites:

Dufrene, M. and P. Legendre.  1997.  Species assemblages and indicator
species:  the need for a flexible asymmetrical approach.  Ecological
Monographs 67:345-366.


----- Original Message -----
From: "Dogan, Enis" <[hidden email]>
Newsgroups: bit.listserv.spssx-l
To: <[hidden email]>
Sent: Friday, June 16, 2006 9:25 AM
Subject: Re: Determining the number of clusters

> SPSS 14 has a new clustering procedure: 2-steps clustering, that
> determines the numb of clusters automatically. It is not very powerful
> though. It usually produces two clusters (my experience) but the nice
> thing about it is that it handles categorical variables as well.
>
> To determine the best number of clusters I would also seek external
> validation.
> Find an external variable (that does not enter the clustering
> procedure); run the clustering with 2, 3, 4, etc... number of clusters
> and see if cluster membership explains the variance in this external
> variable. The external variable should, of course, be related to the
> clusters to begin with.
>
> Hope this helps
>
> You might also want to consider Latent Class analysis for this
> purpose...
>
>
> Enis
>
>
>
> -----Original Message-----
> From: SPSSX(r) Discussion [mailto:[hidden email]] On Behalf Of
> Christian Bautista
> Sent: Friday, June 16, 2006 10:55 AM
> To: [hidden email]
> Subject: Determining the number of clusters
>
> I'm applying a hierarchical cluster analysis in order to determine
> groups
> of cases. As you know SPSS give us a range of potential number of
> clusters.
> However, is there any methodology or specific procedure to follow to
> define
> what is the most correct number of clusters?
>
> Thanks,
>
> /Christian
>